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Research

On the Computational Cost of Knowledge Graph Embeddings

Authors: Victor Charpenay, Mansour Zoubeirou A Mayaki, and Antoine Zimmermann

Published in: TGDK, Volume 4, Issue 1 (2026). Transactions on Graph Data and Knowledge, Volume 4, Issue 1

Abstract

Over a decade, numerous Knowledge Graph Embedding (KGE) models have been designed and evaluated on reference datasets, always with increasing performance. In this paper, we re-evaluate these models with respect to their computational efficiency during training, by estimating the computational cost of the procedure expressed in floating-point operations. We design a cost model based on analytical expressions and apply it on a collection of 20 KGE models, representative of the state-of-the-art. We show that dimensionality or parameter efficiency, used in the literature to compare models with each other, are not suitable to evaluate the true cost of models. Through fixed-budget experiments, a novel approach to evaluate KGE models based on cost estimates, we re-assess the relative performance of model families compared to the state-of-the-art. Bilinear models such as ComplEx underperform with a low computational budget while hyperbolic linear models appear to offer no particular benefit compared to simpler Euclidian models, especially the MuRE model. Neural models, such as ConvE or CompGCN, achieve reasonable performance in the literature but their high computational cost appears unnecessary when compared with other models. The trade-off between efficiency and expressivity of both linear and neural models is to be further explored.

Cite as

Victor Charpenay, Mansour Zoubeirou A Mayaki, and Antoine Zimmermann. On the Computational Cost of Knowledge Graph Embeddings. In Transactions on Graph Data and Knowledge (TGDK), Volume 4, Issue 1, pp. 1:1-1:30, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)

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@Article{charpenay_et_al:TGDK.4.1.1,
  author =	{Charpenay, Victor and Zoubeirou A Mayaki, Mansour and Zimmermann, Antoine},
  title =	{{On the Computational Cost of Knowledge Graph Embeddings}},
  journal =	{Transactions on Graph Data and Knowledge},
  pages =	{1:1--1:30},
  ISSN =	{2942-7517},
  year =	{2026},
  volume =	{4},
  number =	{1},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/TGDK.4.1.1},
  URN =		{urn:nbn:de:0030-drops-256863},
  doi =		{10.4230/TGDK.4.1.1},
  annote =	{Keywords: Knowledge Graph Embedding, Parameter Efficiency, Computational Budget, Green AI}
}

Document

DOI: 10.4230/LIPIcs.ICDT.2026.8

Neither Cover nor Pack: Distributed Worst-Case Optimality of Degree-2 Joins

Authors: Heba Aamer, Xiao Hu, and Bas Ketsman

Published in: LIPIcs, Volume 365, 29th International Conference on Database Theory (ICDT 2026)

Abstract

We study the worst-case communication complexity of the join query evaluation problem over large-scale data in distributed shared-nothing systems under the MPC model. We focus on multi-round MPC algorithms that run in constant number of rounds. The problem is well-understood for a few classes of queries, mainly the class of acyclic queries and the class of graph-like queries. For queries not belonging to either class, the complexity picture is much less clear. We study the class of degree-two queries and fragments thereof. In this paper, we tighten the gap between the upper and lower bounds for the studied classes and establish worst-case optimality for some fragments of the considered classes. We also debunk a well-believed conjecture about which query-related quantity, in the worst-case, optimally captures the communication complexity of the studied problem.

Cite as

Heba Aamer, Xiao Hu, and Bas Ketsman. Neither Cover nor Pack: Distributed Worst-Case Optimality of Degree-2 Joins. In 29th International Conference on Database Theory (ICDT 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 365, pp. 8:1-8:20, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)

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@InProceedings{aamer_et_al:LIPIcs.ICDT.2026.8,
  author =	{Aamer, Heba and Hu, Xiao and Ketsman, Bas},
  title =	{{Neither Cover nor Pack: Distributed Worst-Case Optimality of Degree-2 Joins}},
  booktitle =	{29th International Conference on Database Theory (ICDT 2026)},
  pages =	{8:1--8:20},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-413-0},
  ISSN =	{1868-8969},
  year =	{2026},
  volume =	{365},
  editor =	{ten Cate, Balder and Funk, Maurice},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2026.8},
  URN =		{urn:nbn:de:0030-drops-256226},
  doi =		{10.4230/LIPIcs.ICDT.2026.8},
  annote =	{Keywords: degree-two joins, worst-case optimality, distributed algorithms}
}

Document

DOI: 10.4230/LIPIcs.ICDT.2026.11

Factorised Representations of Join Queries: Tight Bounds and a New Dichotomy

Authors: Christoph Berkholz and Harry Vinall-Smeeth

Published in: LIPIcs, Volume 365, 29th International Conference on Database Theory (ICDT 2026)

Abstract

A common theme in factorised databases and knowledge compilation is the representation of solution sets in a useful yet succinct data structure. In this paper, we study the representation of the result of join queries (or, equivalently, the set of homomorphisms between two relational structures). We focus on the very general format of {∪,×}-circuits - also known as d-representations or DNNF circuits - and aim to find the limits of this approach. In prior work, it has been shown that there always exists a {∪,×}-circuit of size N^O(subw) representing the query result, where N is the size of the database and subw the submodular width of the query. If the arity of all relations is bounded by a constant, then subw is linear in the treewidth tw of the query. In this setting, the authors of this paper proved a lower bound of N^Ω(tw^ε) on the circuit size (ICALP 2023), where ε > 0 depends on the excluded grid theorem. Our first main contribution is to improve this lower bound to N^Ω(tw), which is tight up to a constant factor in the exponent. Our second contribution is a N^Ω(subw^{1/4}) lower bound on the circuit size for join queries over relations of unbounded arity. Both lower bounds are unconditional lower bounds on the circuit size for well-chosen database instances. Their proofs use a combination of structural (hyper)graph theory with communication complexity in a simple yet novel way. While the second lower bound is asymptotically equivalent to Marx’s conditional bound on the decision complexity (JACM 2013), our N^Θ(tw) bound in the bounded arity setting is tight, while the best conditional bound on the decision complexity is N^Ω(tw/log tw). Note that removing this logarithmic factor in the decision setting is a major open problem.

Cite as

Christoph Berkholz and Harry Vinall-Smeeth. Factorised Representations of Join Queries: Tight Bounds and a New Dichotomy. In 29th International Conference on Database Theory (ICDT 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 365, pp. 11:1-11:20, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)

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@InProceedings{berkholz_et_al:LIPIcs.ICDT.2026.11,
  author =	{Berkholz, Christoph and Vinall-Smeeth, Harry},
  title =	{{Factorised Representations of Join Queries: Tight Bounds and a New Dichotomy}},
  booktitle =	{29th International Conference on Database Theory (ICDT 2026)},
  pages =	{11:1--11:20},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-413-0},
  ISSN =	{1868-8969},
  year =	{2026},
  volume =	{365},
  editor =	{ten Cate, Balder and Funk, Maurice},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2026.11},
  URN =		{urn:nbn:de:0030-drops-256255},
  doi =		{10.4230/LIPIcs.ICDT.2026.11},
  annote =	{Keywords: join queries, homomorphisms, factorised databases, succinct representation, knowledge compilation, lower bounds}
}

Document

DOI: 10.4230/LIPIcs.ICDT.2026.21

First-Order Rewritability of Rule-Based Ontology Mediated Queries with Negation

Authors: Georg Gottlob, Marco Manna, Andreas Pieris, and Aldo Ricioppo

Published in: LIPIcs, Volume 365, 29th International Conference on Database Theory (ICDT 2026)

Abstract

The idea of using an ontology to enrich user queries with domain knowledge has attracted considerable attention from the database and KR communities during the last fifteen years or so. The ontology and the user query can be conveniently seen as two components of one composite query, called ontology-mediated query (omq), while an omq language (OL,QL) collects all such omqs where the ontology is expressed using the ontology language OL and the user query comes from the query language QL. The evaluation problem for rule-based omq languages of the form (OL,CQ), where OL is a rule-based ontology language, i.e., it collects ontologies modelled using tuple-generating dependencies (a.k.a. existential rules), and CQ is the language of conjunctive queries, has been extensively studied in the literature. In particular, the notion of first-order rewritability of such languages, i.e., the property of being able to rewrite every omq from the language in question to an equivalent first-order query, has been studied in depth. This research effort led an algorithmic characterization of when a rule-based omq language (OL,CQ) is first-order rewritable. More precisely, there is a uniform algorithm Rewrite such that, for every rule-based ontology language OL, the omq language (OL,CQ) is first-order rewritable iff for every omq O from (OL,CQ), the algorithm Rewrite on input O terminates and constructs a first-order rewriting of O. The question that we are interested in is whether the above algorithmic characterization can be extended to rule-based omq languages of the form (OL,nCQ), where nCQ is the language of conjunctive queries with the useful feature of negation. The goal of this work is to initiate effort towards the settlement of the above highly non-trivial question. To this end, we provide a new algorithm, which is a non-trivial extension of the algorithm Rewrite for positive omqs, and show the following: under the Skolem semantics, a well-established approach for defining the answer to a rule-based omq when the user query can use negation, the proposed algorithm is a first-order rewriter for (OL,nCQ), where OL is the language of linear or acyclic tuple-generating dependencies, two central rule-based ontology languages that ensure first-order rewritability for positive omqs. We strongly believe that the new algorithm can serve as a good starting point towards the full settlement of our main question.

Cite as

Georg Gottlob, Marco Manna, Andreas Pieris, and Aldo Ricioppo. First-Order Rewritability of Rule-Based Ontology Mediated Queries with Negation. In 29th International Conference on Database Theory (ICDT 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 365, pp. 21:1-21:20, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)

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@InProceedings{gottlob_et_al:LIPIcs.ICDT.2026.21,
  author =	{Gottlob, Georg and Manna, Marco and Pieris, Andreas and Ricioppo, Aldo},
  title =	{{First-Order Rewritability of Rule-Based Ontology Mediated Queries with Negation}},
  booktitle =	{29th International Conference on Database Theory (ICDT 2026)},
  pages =	{21:1--21:20},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-413-0},
  ISSN =	{1868-8969},
  year =	{2026},
  volume =	{365},
  editor =	{ten Cate, Balder and Funk, Maurice},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2026.21},
  URN =		{urn:nbn:de:0030-drops-256353},
  doi =		{10.4230/LIPIcs.ICDT.2026.21},
  annote =	{Keywords: ontology-mediated queries, tuple-generating dependencies, conjunctive queries with negation, first-order rewritability}
}

Document

Invited Paper

DOI: 10.4230/OASIcs.RW.2024/2025.5

Inconsistency-Tolerant Semantics Based on (Preferred) Repairs (Invited Paper)

Authors: Camille Bourgaux

Published in: OASIcs, Volume 138, Joint Proceedings of the 20th and 21st Reasoning Web Summer Schools (RW 2024 & RW 2025)

Abstract

Real-world datasets are plagued by data quality issues which may render the data inconsistent w.r.t. a set of constraints, be they given by database integrity constraints or ontologies. A prominent way to handle such inconsistent data is to use inconsistency-tolerant semantics to obtain meaningful answers to queries. Most of these semantics are based on some notion of repairs, which represent ways of restoring the data consistency. The most basic kind of repairs is that of subset repairs, which are maximal consistent subsets of the dataset. However, in many scenarios, one can define preferred repairs based on some preference information. These lecture notes present inconsistency-tolerant semantics, focusing on the repair-based ones, then review different kinds of preferred repairs that have been considered in the literature. We present in particular the relationships between different kinds of preferred repairs and other notions related to inconsistency handling, the computational complexity of reasoning with (preferred) repairs, and some implementations.

Cite as

Camille Bourgaux. Inconsistency-Tolerant Semantics Based on (Preferred) Repairs (Invited Paper). In Joint Proceedings of the 20th and 21st Reasoning Web Summer Schools (RW 2024 & RW 2025). Open Access Series in Informatics (OASIcs), Volume 138, pp. 5:1-5:67, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)

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@InProceedings{bourgaux:OASIcs.RW.2024/2025.5,
  author =	{Bourgaux, Camille},
  title =	{{Inconsistency-Tolerant Semantics Based on (Preferred) Repairs}},
  booktitle =	{Joint Proceedings of the 20th and 21st Reasoning Web Summer Schools (RW 2024 \& RW 2025)},
  pages =	{5:1--5:67},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-405-5},
  ISSN =	{2190-6807},
  year =	{2025},
  volume =	{138},
  editor =	{Artale, Alessandro and Bienvenu, Meghyn and Garc{\'\i}a, Yazm{\'\i}n Ib\'{a}\~{n}ez and Murlak, Filip},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.RW.2024/2025.5},
  URN =		{urn:nbn:de:0030-drops-250504},
  doi =		{10.4230/OASIcs.RW.2024/2025.5},
  annote =	{Keywords: Knowledge bases, databases, inconsistency handling, repairs, preferences}
}

Document

Invited Paper

DOI: 10.4230/OASIcs.RW.2024/2025.9

Reasoning About Time in DatalogMTL: Course Notes (Invited Paper)

Authors: Przemysław Andrzej Wałęga

Published in: OASIcs, Volume 138, Joint Proceedings of the 20th and 21st Reasoning Web Summer Schools (RW 2024 & RW 2025)

Abstract

Many real-world applications, such as those in healthcare, finance, and logistics, require reasoning over temporal data. Standard rule-based languages like Datalog, however, lack explicit mechanisms for handling time and temporal dependencies. In this chapter, we discussDatalogMTL, an extension of Datalog with operators frommetric temporal logic that allow to express complex temporal properties. We focus on reasoning algorithms for DatalogMTL, discussing bothmaterialisation, based on fixpoint applications of the immediate consequence operator, and anovel saturation-based extensionthat detects and halts infinite derivations, ensuring both completeness and termination of reasoning.

Cite as

Przemysław Andrzej Wałęga. Reasoning About Time in DatalogMTL: Course Notes (Invited Paper). In Joint Proceedings of the 20th and 21st Reasoning Web Summer Schools (RW 2024 & RW 2025). Open Access Series in Informatics (OASIcs), Volume 138, pp. 9:1-9:23, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)

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@InProceedings{walega:OASIcs.RW.2024/2025.9,
  author =	{Wa{\l}\k{e}ga, Przemys{\l}aw Andrzej},
  title =	{{Reasoning About Time in DatalogMTL: Course Notes}},
  booktitle =	{Joint Proceedings of the 20th and 21st Reasoning Web Summer Schools (RW 2024 \& RW 2025)},
  pages =	{9:1--9:23},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-405-5},
  ISSN =	{2190-6807},
  year =	{2025},
  volume =	{138},
  editor =	{Artale, Alessandro and Bienvenu, Meghyn and Garc{\'\i}a, Yazm{\'\i}n Ib\'{a}\~{n}ez and Murlak, Filip},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.RW.2024/2025.9},
  URN =		{urn:nbn:de:0030-drops-250546},
  doi =		{10.4230/OASIcs.RW.2024/2025.9},
  annote =	{Keywords: DatalogMTL, Logic Programming, Temporal Reasoning}
}

Document

Survey

DOI: 10.4230/TGDK.3.2.1

Resilience in Knowledge Graph Embeddings

Authors: Arnab Sharma, N'Dah Jean Kouagou, and Axel-Cyrille Ngonga Ngomo

Published in: TGDK, Volume 3, Issue 2 (2025). Transactions on Graph Data and Knowledge, Volume 3, Issue 2

Abstract

In recent years, knowledge graphs have gained interest and witnessed widespread applications in various domains, such as information retrieval, question-answering, recommendation systems, amongst others. Large-scale knowledge graphs to this end have demonstrated their utility in effectively representing structured knowledge. To further facilitate the application of machine learning techniques, knowledge graph embedding models have been developed. Such models can transform entities and relationships within knowledge graphs into vectors. However, these embedding models often face challenges related to noise, missing information, distribution shift, adversarial attacks, etc. This can lead to sub-optimal embeddings and incorrect inferences, thereby negatively impacting downstream applications. While the existing literature has focused so far on adversarial attacks on KGE models, the challenges related to the other critical aspects remain unexplored. In this paper, we, first of all, give a unified definition of resilience, encompassing several factors such as generalisation, in-distribution generalization, distribution adaption, and robustness. After formalizing these concepts for machine learning in general, we define them in the context of knowledge graphs. To find the gap in the existing works on resilience in the context of knowledge graphs, we perform a systematic survey, taking into account all these aspects mentioned previously. Our survey results show that most of the existing works focus on a specific aspect of resilience, namely robustness. After categorizing such works based on their respective aspects of resilience, we discuss the challenges and future research directions.

Cite as

Arnab Sharma, N'Dah Jean Kouagou, and Axel-Cyrille Ngonga Ngomo. Resilience in Knowledge Graph Embeddings. In Transactions on Graph Data and Knowledge (TGDK), Volume 3, Issue 2, pp. 1:1-1:38, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)

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@Article{sharma_et_al:TGDK.3.2.1,
  author =	{Sharma, Arnab and Kouagou, N'Dah Jean and Ngomo, Axel-Cyrille Ngonga},
  title =	{{Resilience in Knowledge Graph Embeddings}},
  journal =	{Transactions on Graph Data and Knowledge},
  pages =	{1:1--1:38},
  ISSN =	{2942-7517},
  year =	{2025},
  volume =	{3},
  number =	{2},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/TGDK.3.2.1},
  URN =		{urn:nbn:de:0030-drops-248117},
  doi =		{10.4230/TGDK.3.2.1},
  annote =	{Keywords: Knowledge graphs, Resilience, Robustness}
}

Document

Short Paper

DOI: 10.4230/LIPIcs.TIME.2025.15

The Temporal Vadalog System (Short Paper)

Authors: Luigi Bellomarini, Livia Blasi, Markus Nissl, and Emanuel Sallinger

Published in: LIPIcs, Volume 355, 32nd International Symposium on Temporal Representation and Reasoning (TIME 2025)

Abstract

The recent resurgence of the Datalog language in the Knowledge Representation and Reasoning community has paved the way for a very promising proposal for temporal extension. DatalogMTL (Datalog with Metric Temporal Operators) is a language that offers a good trade-off between computational complexity and expressive power. However, existing implementations are still preliminary or prototypical. In this extended abstract, we give a brief overview of Temporal Vadalog, a system supporting reasoning over DatalogMTL programs built upon an engineered architecture and adopted in production scenarios in the financial setting.

Cite as

Luigi Bellomarini, Livia Blasi, Markus Nissl, and Emanuel Sallinger. The Temporal Vadalog System (Short Paper). In 32nd International Symposium on Temporal Representation and Reasoning (TIME 2025). Leibniz International Proceedings in Informatics (LIPIcs), Volume 355, pp. 15:1-15:8, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)

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@InProceedings{bellomarini_et_al:LIPIcs.TIME.2025.15,
  author =	{Bellomarini, Luigi and Blasi, Livia and Nissl, Markus and Sallinger, Emanuel},
  title =	{{The Temporal Vadalog System}},
  booktitle =	{32nd International Symposium on Temporal Representation and Reasoning (TIME 2025)},
  pages =	{15:1--15:8},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-401-7},
  ISSN =	{1868-8969},
  year =	{2025},
  volume =	{355},
  editor =	{Vidal, Thierry and Wa{\l}\k{e}ga, Przemys{\l}aw Andrzej},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.TIME.2025.15},
  URN =		{urn:nbn:de:0030-drops-244611},
  doi =		{10.4230/LIPIcs.TIME.2025.15},
  annote =	{Keywords: temporal reasoning, Datalog, DatalogMTL}
}

Document

DOI: 10.4230/LIPIcs.ICDT.2025.8

Enumeration of Minimal Hitting Sets Parameterized by Treewidth

Authors: Batya Kenig and Dan Shlomo Mizrahi

Published in: LIPIcs, Volume 328, 28th International Conference on Database Theory (ICDT 2025)

Abstract

Enumerating the minimal hitting sets of a hypergraph is a problem which arises in many data management applications that include constraint mining, discovering unique column combinations, and enumerating database repairs. Previously, Eiter et al. [Thomas Eiter et al., 2003] showed that the minimal hitting sets of an n-vertex hypergraph, with treewidth w, can be enumerated with delay O^*(n^w) (ignoring polynomial factors), with space requirements that scale with the output size. We improve this to fixed-parameter-linear delay, following an FPT preprocessing phase. The memory consumption of our algorithm is exponential with respect to the treewidth of the hypergraph.

Cite as

Batya Kenig and Dan Shlomo Mizrahi. Enumeration of Minimal Hitting Sets Parameterized by Treewidth. In 28th International Conference on Database Theory (ICDT 2025). Leibniz International Proceedings in Informatics (LIPIcs), Volume 328, pp. 8:1-8:20, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)

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@InProceedings{kenig_et_al:LIPIcs.ICDT.2025.8,
  author =	{Kenig, Batya and Mizrahi, Dan Shlomo},
  title =	{{Enumeration of Minimal Hitting Sets Parameterized by Treewidth}},
  booktitle =	{28th International Conference on Database Theory (ICDT 2025)},
  pages =	{8:1--8:20},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-364-5},
  ISSN =	{1868-8969},
  year =	{2025},
  volume =	{328},
  editor =	{Roy, Sudeepa and Kara, Ahmet},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2025.8},
  URN =		{urn:nbn:de:0030-drops-229498},
  doi =		{10.4230/LIPIcs.ICDT.2025.8},
  annote =	{Keywords: Enumeration, Hitting sets}
}

Document

DOI: 10.4230/LIPIcs.ICDT.2025.6

PAC: Computing Join Queries with Semi-Covers

Authors: Heba Aamer and Bas Ketsman

Published in: LIPIcs, Volume 328, 28th International Conference on Database Theory (ICDT 2025)

Abstract

An increased and growing interest in large-scale data processing has triggered a demand for specialized algorithms that thrive in massively parallel shared-nothing systems. To answer the question of how to efficiently compute join queries in this setting, a rich line of research has emerged specifically for the Massively Parallel Communication (MPC) model. In the MPC model, algorithms are executed in rounds, with each round consisting of a synchronized communication phase and a separate local computation phase. The main cost measure is the load of the algorithm, defined as the maximum number of messages received by any server in any round. We study worst-case optimal algorithms for the join query evaluation problem in the constant-round MPC model. In the single-round variant of MPC, the worst-case optimal load for this problem is well understood and algorithms exist that guarantee this load for any join query. In the constant-round variant of MPC, queries can often be computed with a lower load compared to the single-round variant, but the worst-case optimal load is only known for specific classes of join queries, including graph-like and acyclic join queries, and the associated algorithms use very different techniques. In this paper, we propose a new constant-round MPC algorithm for computing join queries. Our algorithm is correct for every join query and its load matches (up to a polylog factor) the worst-case optimal load for at least all join queries that are acyclic or graph-like.

Cite as

Heba Aamer and Bas Ketsman. PAC: Computing Join Queries with Semi-Covers. In 28th International Conference on Database Theory (ICDT 2025). Leibniz International Proceedings in Informatics (LIPIcs), Volume 328, pp. 6:1-6:20, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)

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@InProceedings{aamer_et_al:LIPIcs.ICDT.2025.6,
  author =	{Aamer, Heba and Ketsman, Bas},
  title =	{{PAC: Computing Join Queries with Semi-Covers}},
  booktitle =	{28th International Conference on Database Theory (ICDT 2025)},
  pages =	{6:1--6:20},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-364-5},
  ISSN =	{1868-8969},
  year =	{2025},
  volume =	{328},
  editor =	{Roy, Sudeepa and Kara, Ahmet},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2025.6},
  URN =		{urn:nbn:de:0030-drops-229474},
  doi =		{10.4230/LIPIcs.ICDT.2025.6},
  annote =	{Keywords: Worst-case optimal load, MPC model, join queries}
}

Document

DOI: 10.4230/LIPIcs.ICDT.2025.17

Partition Constraints for Conjunctive Queries: Bounds and Worst-Case Optimal Joins

Authors: Kyle Deeds and Timo Camillo Merkl

Published in: LIPIcs, Volume 328, 28th International Conference on Database Theory (ICDT 2025)

Abstract

In the last decade, various works have used statistics on relations to improve both the theory and practice of conjunctive query execution. Starting with the AGM bound which took advantage of relation sizes, later works incorporated statistics like functional dependencies and degree constraints. Each new statistic prompted work along two lines; bounding the size of conjunctive query outputs and worst-case optimal join algorithms. In this work, we continue in this vein by introducing a new statistic called a partition constraint. This statistic captures latent structure within relations by partitioning them into sub-relations which each have much tighter degree constraints. We show that this approach can both refine existing cardinality bounds and improve existing worst-case optimal join algorithms.

Cite as

Kyle Deeds and Timo Camillo Merkl. Partition Constraints for Conjunctive Queries: Bounds and Worst-Case Optimal Joins. In 28th International Conference on Database Theory (ICDT 2025). Leibniz International Proceedings in Informatics (LIPIcs), Volume 328, pp. 17:1-17:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)

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@InProceedings{deeds_et_al:LIPIcs.ICDT.2025.17,
  author =	{Deeds, Kyle and Merkl, Timo Camillo},
  title =	{{Partition Constraints for Conjunctive Queries: Bounds and Worst-Case Optimal Joins}},
  booktitle =	{28th International Conference on Database Theory (ICDT 2025)},
  pages =	{17:1--17:18},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-364-5},
  ISSN =	{1868-8969},
  year =	{2025},
  volume =	{328},
  editor =	{Roy, Sudeepa and Kara, Ahmet},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2025.17},
  URN =		{urn:nbn:de:0030-drops-229588},
  doi =		{10.4230/LIPIcs.ICDT.2025.17},
  annote =	{Keywords: Worst-Case Optimal Joins, Cardinality Bounds, Degeneracy, Degree Constraints, Partition Constraints}
}

Document

DOI: 10.4230/TGDK.2.3.2

Strong Faithfulness for ELH Ontology Embeddings

Authors: Victor Lacerda, Ana Ozaki, and Ricardo Guimarães

Published in: TGDK, Volume 2, Issue 3 (2024). Transactions on Graph Data and Knowledge, Volume 2, Issue 3

Abstract

Ontology embedding methods are powerful approaches to represent and reason over structured knowledge in various domains. One advantage of ontology embeddings over knowledge graph embeddings is their ability to capture and impose an underlying schema to which the model must conform. Despite advances, most current approaches do not guarantee that the resulting embedding respects the axioms the ontology entails. In this work, we formally prove that normalized ELH has the strong faithfulness property on convex geometric models, which means that there is an embedding that precisely captures the original ontology. We present a region-based geometric model for embedding normalized ELH ontologies into a continuous vector space. To prove strong faithfulness, our construction takes advantage of the fact that normalized ELH has a finite canonical model. We first prove the statement assuming (possibly) non-convex regions, allowing us to keep the required dimensions low. Then, we impose convexity on the regions and show the property still holds. Finally, we consider reasoning tasks on geometric models and analyze the complexity in the class of convex geometric models used for proving strong faithfulness.

Cite as

Victor Lacerda, Ana Ozaki, and Ricardo Guimarães. Strong Faithfulness for ELH Ontology Embeddings. In Transactions on Graph Data and Knowledge (TGDK), Volume 2, Issue 3, pp. 2:1-2:29, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@Article{lacerda_et_al:TGDK.2.3.2,
  author =	{Lacerda, Victor and Ozaki, Ana and Guimar\~{a}es, Ricardo},
  title =	{{Strong Faithfulness for ELH Ontology Embeddings}},
  journal =	{Transactions on Graph Data and Knowledge},
  pages =	{2:1--2:29},
  ISSN =	{2942-7517},
  year =	{2024},
  volume =	{2},
  number =	{3},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/TGDK.2.3.2},
  URN =		{urn:nbn:de:0030-drops-225965},
  doi =		{10.4230/TGDK.2.3.2},
  annote =	{Keywords: Knowledge Graph Embeddings, Ontologies, Description Logic}
}

Document

Invited Talk

DOI: 10.4230/LIPIcs.TIME.2024.3

Rule-Based Temporal Reasoning: Exploring DatalogMTL (Invited Talk)

Authors: Przemysław Andrzej Wałęga

Published in: LIPIcs, Volume 318, 31st International Symposium on Temporal Representation and Reasoning (TIME 2024)

Abstract

I will introduce DatalogMTL - an extension of Datalog, augmenting it with operators known from metric temporal logic (MTL). DatalogMTL is an expressive language which allows us for complex temporal reasoning over a dense timeline and, at the same time, remains decidable. I will provide an overview of research on DatalogMTL by discussing its computational complexity, syntactic and semantic modifications, practical reasoning approaches, applications, and future research directions.

Cite as

Przemysław Andrzej Wałęga. Rule-Based Temporal Reasoning: Exploring DatalogMTL (Invited Talk). In 31st International Symposium on Temporal Representation and Reasoning (TIME 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 318, pp. 3:1-3:3, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{walega:LIPIcs.TIME.2024.3,
  author =	{Wa{\l}\k{e}ga, Przemys{\l}aw Andrzej},
  title =	{{Rule-Based Temporal Reasoning: Exploring DatalogMTL}},
  booktitle =	{31st International Symposium on Temporal Representation and Reasoning (TIME 2024)},
  pages =	{3:1--3:3},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-349-2},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{318},
  editor =	{Sala, Pietro and Sioutis, Michael and Wang, Fusheng},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.TIME.2024.3},
  URN =		{urn:nbn:de:0030-drops-212106},
  doi =		{10.4230/LIPIcs.TIME.2024.3},
  annote =	{Keywords: Temporal Datalog, Temporal Logic Programming, Temporal Reasoning}
}

Document

DOI: 10.4230/OASIcs.Tannen.1

Explaining Enterprise Knowledge Graphs with Large Language Models and Ontological Reasoning

Authors: Teodoro Baldazzi, Luigi Bellomarini, Stefano Ceri, Andrea Colombo, Andrea Gentili, Emanuel Sallinger, and Paolo Atzeni

Published in: OASIcs, Volume 119, The Provenance of Elegance in Computation - Essays Dedicated to Val Tannen (2024)

Abstract

In recent times, the demand for transparency and accountability in AI-driven decisions has intensified, particularly in high-stakes domains like finance and bio-medicine. This focus on the provenance of AI-generated conclusions underscores the need for decision-making processes that are not only transparent but also readily interpretable by humans, to built trust of both users and stakeholders. In this context, the integration of state-of-the-art Large Language Models (LLMs) with logic-oriented Enterprise Knowledge Graphs (EKGs) and the broader scope of Knowledge Representation and Reasoning (KRR) methodologies is currently at the cutting edge of industrial and academic research across numerous data-intensive areas. Indeed, such a synergy is paramount as LLMs bring a layer of adaptability and human-centric understanding that complements the structured insights of EKGs. Conversely, the central role of ontological reasoning is to capture the domain knowledge, accurately handling complex tasks over a given realm of interest, and to infuse the process with transparency and a clear provenance-based explanation of the conclusions drawn, addressing the fundamental challenge of LLMs' inherent opacity and fostering trust and accountability in AI applications. In this paper, we propose a novel neuro-symbolic framework that leverages the underpinnings of provenance in ontological reasoning to enhance state-of-the-art LLMs with domain awareness and explainability, enabling them to act as natural language interfaces to EKGs.

Cite as

Teodoro Baldazzi, Luigi Bellomarini, Stefano Ceri, Andrea Colombo, Andrea Gentili, Emanuel Sallinger, and Paolo Atzeni. Explaining Enterprise Knowledge Graphs with Large Language Models and Ontological Reasoning. In The Provenance of Elegance in Computation - Essays Dedicated to Val Tannen. Open Access Series in Informatics (OASIcs), Volume 119, pp. 1:1-1:20, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{baldazzi_et_al:OASIcs.Tannen.1,
  author =	{Baldazzi, Teodoro and Bellomarini, Luigi and Ceri, Stefano and Colombo, Andrea and Gentili, Andrea and Sallinger, Emanuel and Atzeni, Paolo},
  title =	{{Explaining Enterprise Knowledge Graphs with Large Language Models and Ontological Reasoning}},
  booktitle =	{The Provenance of Elegance in Computation - Essays Dedicated to Val Tannen},
  pages =	{1:1--1:20},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-320-1},
  ISSN =	{2190-6807},
  year =	{2024},
  volume =	{119},
  editor =	{Amarilli, Antoine and Deutsch, Alin},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.Tannen.1},
  URN =		{urn:nbn:de:0030-drops-200971},
  doi =		{10.4230/OASIcs.Tannen.1},
  annote =	{Keywords: provenance, ontological reasoning, language models, knowledge graphs}
}

Document

DOI: 10.4230/OASIcs.Tannen.9

On the Impact of Provenance Semiring Theory on the Design of a Provenance-Aware Database System

Authors: Pierre Senellart

Published in: OASIcs, Volume 119, The Provenance of Elegance in Computation - Essays Dedicated to Val Tannen (2024)

Abstract

We report on the impact that the theory of provenance semirings, developed by Val Tannen and his collaborators, has had on the design on a practical system for maintaining the provenance of query results over a relational database, namely ProvSQL.

Cite as

Pierre Senellart. On the Impact of Provenance Semiring Theory on the Design of a Provenance-Aware Database System. In The Provenance of Elegance in Computation - Essays Dedicated to Val Tannen. Open Access Series in Informatics (OASIcs), Volume 119, pp. 9:1-9:10, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{senellart:OASIcs.Tannen.9,
  author =	{Senellart, Pierre},
  title =	{{On the Impact of Provenance Semiring Theory on the Design of a Provenance-Aware Database System}},
  booktitle =	{The Provenance of Elegance in Computation - Essays Dedicated to Val Tannen},
  pages =	{9:1--9:10},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-320-1},
  ISSN =	{2190-6807},
  year =	{2024},
  volume =	{119},
  editor =	{Amarilli, Antoine and Deutsch, Alin},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.Tannen.9},
  URN =		{urn:nbn:de:0030-drops-201050},
  doi =		{10.4230/OASIcs.Tannen.9},
  annote =	{Keywords: provenance, provenance semiring, ProvSQL}
}

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